POWER SUPPLY DEVICE FOR VEHICLE

Provided is a vehicle power supply device that is capable of executing non-synchronous rectification control and synchronous rectification control while switching therebetween and can suppress, during switching from the non-synchronous rectification control to the synchronous rectification control, an output voltage value from significantly deviating from a target voltage value. If a determination unit determines, during the execution of the non-synchronous rectification control, that a current-increasing state arises, a driving unit performs switching to the synchronous rectification control in which a PWM signal with a duty cycle of a fixed value is supplied to a first switch unit, and then performs the synchronous rectification control in which a PWM signal with a duty cycle that is calculated by a feedback operation unit based on the target output voltage value and the detection result of the detecting unit is supplied to the first switch unit.